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This paper deals with the reactivation of three test benches of high, medium and low power electric generators for hydraulic energy conversion in the University of Carabobo Hydraulic Laboratory. The method involves three stages: i) Description of three high, medium and low power electric generators for hydraulic energy conversion, ii) Rehabilitation of three high, medium and low power electric generators for hydraulic energy conversion and iii) Evaluation of performance indexes of high, medium and low power electric generators for hydraulic conversion. The results indicate that for the low power electric generator, the position angle of the distributor blades is an experimental factor that has a significant effect on the response variables studied. With respect to the medium and high power electric generators, the most influential factor on operation and power generation is the flow supplied., El presente trabajo trata sobre la reactivación de tres bancos de pruebas de generadores eléctricos de alta, media y baja potencia para conversión de energía hidráulica en el Laboratorio de Hidráulica de la Universidad de Carabobo. El método involucra tres etapas: i) Descripción de tres generadores eléctricos de alta, media y baja potencia para conversión de energía hidráulica, ii) Rehabilitación de generadores eléctricos de alta, media y baja potencia para conversión de energía hidráulica y iii) Evaluación de índices de desempeño de generadores eléctricos de alta, media y baja potencia para conversión de energía hidráulica. Los resultados indican que para el generador eléctrico de baja potencia, el ángulo de posición de las palas del distribuidor es el factor experimental que tiene un efecto significativo en las variables de respuesta estudiadas. Con respecto a los generadores eléctricos de media y alta potencia, el factor que más influye en el funcionamiento y generación de energía es el caudal suministrado.

This paper deals with the reactivation of three test benches of high, medium and low power electric generators for hydraulic energy conversion in the University of Carabobo Hydraulic Laboratory. The method involves three stages: i) Description of three high, medium and low power electric generators for hydraulic energy conversion, ii) Rehabilitation of three high, medium and low power electric generators for hydraulic energy conversion and iii) Evaluation of performance indexes of high, medium and low power electric generators for hydraulic conversion. The results indicate that for the low power electric generator, the position angle of the distributor blades is an experimental factor that has a significant effect on the response variables studied. With respect to the medium and high power electric generators, the most influential factor on operation and power generation is the flow supplied., El presente trabajo trata sobre la reactivación de tres bancos de pruebas de generadores eléctricos de alta, media y baja potencia para conversión de energía hidráulica en el Laboratorio de Hidráulica de la Universidad de Carabobo. El método involucra tres etapas: i) Descripción de tres generadores eléctricos de alta, media y baja potencia para conversión de energía hidráulica, ii) Rehabilitación de generadores eléctricos de alta, media y baja potencia para conversión de energía hidráulica y iii) Evaluación de índices de desempeño de generadores eléctricos de alta, media y baja potencia para conversión de energía hidráulica. Los resultados indican que para el generador eléctrico de baja potencia, el ángulo de posición de las palas del distribuidor es el factor experimental que tiene un efecto significativo en las variables de respuesta estudiadas. Con respecto a los generadores eléctricos de media y alta potencia, el factor que más influye en el funcionamiento y generación de energía es el caudal suministrado.

Un disque aubagé monobloc, ou blisk, est un élément usiné en un seul bloc composé d’un disque et de plusieurs pales, qui est de plus en plus utilisé dans les turboréacteurs d’avion. De petites déviations des propriétés mécaniques et de la géométrie sont inévitables d’un secteur, ou d’une pale, à l’autre. En opération, ces déviations causent le mistuning qui peut mener à l’amplification de la réponse vibratoire et à la localisation des contraintes sur quelques pales seulement. Il est donc important de bien identifier le mistuning et de prévoir son effet avant son intégration dans un moteur d’avion. De plus, pour éviter de perturber l’identification du mistuning, un système d’excitation acoustique sans contact est préférable. Une étude numérique est d’abord présentée dans le but d’établir une procédure d’identification robuste et systématique du mistuning en simulant un jeu de données expérimentales désaccordées pour un blisk académique de 24 pales. La méthode Component Mode Mistuning IDentification (CMM ID) est utilisée pour la thèse. Comme le blisk académique se situe à la limite des hypothèses du CMM ID, une contribution de ce travail de thèse consiste en la validation expérimental de deux améliorations à la méthode visant à la rendre plus robuste est validée. Ces deux améliorations sont la méthode CMM ID étendue développée par Lim [52] et la sélection du sous-ensemble optimal de modes de système accordés développée par Madden et al. [55]. À partir de l’étude numérique, une procédure détaillée de la sélection systématique des données désaccordées à mesurer est proposée. Celle-ci est validée expérimentalement avec succès sur le blisk académique ainsi que sur un blisk industriel de 56 pales, en utilisant le système d’excitation acoustique de 24 hautparleurs développé générant un excitation de type Traveling Wave Excitation (TWE). Trois notions sont également étudiées afin de proposer une excitation acoustique adaptée à une grande variété de pales. Tout d’abord, on co, A one-piece bladed disk, or blisk, is an element machined in a single block consisting of a disk and several blades which is increasingly used in aircraft turbojet engines. Small deviations in mechanical properties and in the geometry are inevitable from one sector, or blade, to another. In operation, these deviations cause mistuning which can lead to the amplification of the vibration response and stress localization on only few blades. It is therefore important to identify the mistuning and predict its effect before integrating a blisk into an aircraft engine. Moreover, to avoid disturbing the mistuning identification, a contactless acoustic excitation system is preferable. A numerical study is first presented that aims at establishing a robust and systematic mistuning identification procedure by simulating an experimental mistuned data set for a 24-blade academic blisk. The use of the Component Mode Mistuning IDentification (CMM ID) method is used throughout the thesis. As the academic blisk lies at the limit of the assumptions of CMM ID, one of the contributions of this work lies in the experimental validation of two major additions to the method aimed at making it more robust are validated. These two additions are the extended CMM ID method developed by Lim [52] and the selection of the optimal subset of tuned system modes developed by Madden et al. [55]. From the numerical study, a detailed procedure for the systematic selection of mistuned data to be measured is proposed. This procedure is experimentally validated with success on the academic blisk as well as on a 56-blade industrial blisk with the developed 24-loudspeaker acoustic excitation system generating a Traveling Wave Excitation (TWE). Additionally, in order to propose an acoustic excitation that is suitable to a large variety of blisks, three notions are investigated. First, it is found that the generation of a k Engine Order (EO) TWE using a smaller number of loudspeakers S than the numbe

Analysis, optimization and uncertainty quantification of the aerodynamic behaviour of turbomachinery components is a fundamental part of the current industrial design process and requires the extensive use of compute-intensive CFD simulations. In this paper we investigate whether graph neural networks can be useful as surrogate models to accelerate the design process, for example in a multi-fidelity framework. Graph neural networks promise to provide good estimates of flow quantities while maintaining the geometric accuracy at a fraction of the computational effort of classical CFD. An application to industrially relevant turbomachinery flows is performed to gain a good understanding of the capabilities and limitations of such methods. We therefore apply a state-of-the-art graph neural network to a turbomachinery setup of industry-relevant mesh size. In particular, a multiscale graph neural network is used to overcome the problems of large information distances when applying message-passing based graph-net blocks to large meshes. The database used to train the network consists of a space-filling DoE of 100 CFD solutions with different geometries. The first use case encompasses the prediction of the flow quantities of the complete fluid domain with 2.5e6 mesh points. The second use case focuses on predicting a single scalar (e.g. pressure or temperature) on surface meshes with up to 30e3 mesh points. In both cases, the networks are employed to predict time-averaged and unsteady flow fields on unstructured meshes of variable point sizes for new geometries not present in the training set. The results demonstrate the proficiency of the approach in predicting time-averaged and unsteady flow quantities on surfaces as well as for full fluid domains for new geometries.

In this study, an infrared system is developed for accurate measurements of surface temperature and heat transfer on fast moving targets. The system was designed for the Oxford Turbine Research Facility, a world-leading experimental facility delivering highly engine representative, scalable heat transfer results for aerospace research. Infrared thermography is employed to acquire temperature maps of high-pressure turbine blades, allowing assessment of surface thermal conditions including heat transfer coefficient, adiabatic wall temperature, Nusselt number, cooling effectiveness, and metal effectiveness. Achieving accurate infrared thermography measurements in rotating turbomachinery experimental conditions is arduous due to reflections from the surroundings, low emissivity of metallic parts, and motion blur resulting from high speed. To overcome these challenges, calibration procedures were developed against a traceable standard using a bespoke steady experimental facility. A method to determine the reflected temperature from surroundings was also validated. Correction for all measurement disturbances is demonstrated to within the accuracy of the primary measurement thermocouple. Finally, the developed calibration method was validated on a fast-moving rotating geometry demonstrating accurate correction for all measurement disturbances, without the need for an in situ calibration. A detailed uncertainty analysis for each calibration step is also presented., Fluid Mechanics

Climate change is a pressing issue. Hydrogen aircraft are an excellent alternative to current kerosene aircraft, and appear to be the most viable long-term solution for net-zero flight. One of the main challenges for hydrogen aircraft is to sustain a low boil-off rate. This research explores the solution of active cooling of the LH2 mixture in the fuel tank. It focusses on the construction of a thermodynamic model for cryogenic liquid hydrogen fuel storage in aircraft, a system model for single-stage Reverse Turbo-Brayton Cryocoolers (RTBC), and the conceptual design of the RTBC’s miniature high-speed compressor. This is used for the integrated modelling of the RTBC, compressor and LH2 fuel tank for an exploration study of the carbon neutral hydrogen concept of the long-range Flying-V aircraft. Results show that the RTBC might offer a valuable addition to the Flying-V design space for boil-off control in addition to careful design of the insulation and tank shape., Aerospace Engineering

In the scope of global decarbonisation, hydrogen has been identified as an essential energy carrier. Not only as an energy storage solution for further electrification in vehicles but also as a primary fuel source in processes that rely on chemical energy which cannot be easily electrified. However, at ambient conditions, hydrogen is also a very sparse gas with a low energy density. This requires it to be either liquified or compressed as a gas for most storage and transport solutions, both of which are rather energy-intensive processes. In the case of compressed hydrogen this leads to a significant amount of potential energy stored in the storage tanks. In current applications, the high pressure hydrogen is then expanded through a valve to reach the system’s desired working pressure. A process in which most of the potential energy stored in the compressed is lost to thermal effects. The research in this thesis is focused on identifying a suitable application in which an expander could be applied to recover part of the potential energy stored in compressed hydrogen and to provide a conceptual design and a thermodynamical analysis of this expander to assess its efficiency and feasibility and has been caried out in collaboration with Ayed Engineering GmbH. The literature study provided an overview of the current hydrogen landscape and the potential applications in which an expander could be applied. These have been evaluated and led to the selection of a hydrogen refuelling station as a suitable application for this purpose. A system model has been developed to replicate a refuelling process in a hydrogen refuelling station and to serve as an operating environment for the to-be-designed expander. Based on the operating parameters of the hydrogen refuelling station, a number of expander designs have been developed, each optimized for the operating conditions in the station at a certain timestep. Empirical loss models have been applied to assess th, Aerospace Engineering

Analysing and developing turbomachinery at off-design conditions requires the usage of robust and efficient Computational Fluid Dynamics (CFD) solvers. With the introduction of the computer, many advancements have been made in the field of numerical methods involving these flow problems. These numerical methods are used in order to solve these complex flow structures that are formed due to the interaction between the rotating machinery and the fluid. With the emergence of new design paradigms using computer-aided optimisation, novel solver methods are required which are able to deal with the increase in computational cost and the convergence difficulties following off-design conditions. One of the CFD solvers that is used for turbomachinery design is the open-source software SU2. SU2 is currently developed partially at the Delft University of Technology, where an increase in solver performance with respect to turbomachinery aerodynamics is greatly desired. The current work provides a numerical study of SU2's current performance with respect to turbomachinery analysis, as this is currently unknown. The current performance of SU2 is to be analysed using steady RANS turbomachinery simulations. The research conducted by Xu et al. \cite{Xu2020} will be used as reference data in order to validate SU2's performance together with data obtained from the CFD solvers CFX and Numeca. The research conducted by Xu et al. resulted in the development of their NUTSCFD solver, which showed strong performance with respect to turbomachinery analysis. Four test cases are set up and used in order to analyse SU2. The test cases that are considered for the numerical study include: the NACA 0012 airfoil, the LS89 turbine cascade, the MTU centrifugal compressor and the 1.5 stage ETH turbine. The first three test cases are validated using the results obtained by the NUTSCFD solver, where the ETH turbine is validated using CFX and Numeca. Following these test cases, SU2's performance, Aerospace Engineering

This paper examines two examples of testing activities of sub-components of a 300kN methalox first-stage rocket engine developed by Pangea Aerospace, namely, theinjectors and the cryogenic pumps. One of the difficulties of these test campaignsis to evaluate the performances of these sub-components without using cryogenicpropellants and in conditions differing from flight conditions.Two different methods were used to replace the cryogenic propellants at extreme pressures and temperatures: the pumps were tested using water to replace both propellants, and the injectors were tested using water and nitrogen to account for the different propellant phases. The correlation, similarity methods, and bench sizing were detailed for both test campaigns, but only the injector test campaign was completed and its results were analyzed.The method to emulate cryogenic fluid behavior in a pump leads to the use of a bench controlling not only pressure and mass flow but also temperature to account for the cavitation effects. Furthermore, the bench must have the capability to pressurize the water under atmospheric pressure, leading to the use of a vacuum pump. The injector test campaign produces results that closely align with theoretical predictions. This enables the selection of the optimal single-element injector design through a quantitative assessment of the discharge coefficient and a qualitative evaluation of the spray angle and atomization. Although these studies are based on strong models, they must be compared to hotfire data and later flight data to be assessed fully, all the more so that the pump test campaign was not performed., I denna rapport behandlas två exempel på provningsaktiviteter för delkomponenter av en methalox-driven 300 kN-klass raketmotor, utvecklad av Pangea Aerospace för användning på förstasteg. Delkomponenterna består av injektorerna samt dekryogena pumparna. En av svårigheterna med provkampanjerna är att utvärdera prestandan hos dessa delkomponenter utan att använda kryogena drivmedel och underförhållanden som skiljer sig från flygförhållandena. Två olika metoder användes för att imitera de kryogena drivmedlen vid extrema tryck och temperaturer. Först testades pumparna med vatten som en ersättning för de båda drivmedlen, och sedan testades injektorerna med både vatten och kväve för att ta hänsyn till de olika aggregations tillstånden. Korrelationen, likhetsmetoderna, samt provbänkstorleken utredes i detalj för bägge testkampanjer, men endast injektortestkampanjen slutfördes och dess resultat analyserades. Metoden för att efterlikna kryogena vätskors beteende i en pump leder till användning av en provbänk som inte bara reglerar tryck och massflöde utan även temperatur för att ta hänsyn till kavitations effekterna. Dessutom måste bänken ha kapacitet att trycksätta vattnet under atmosfärstryck, vilket leder till användning av en vakuumpump. Injektortestkampanjen ger resultat som ligger nära de teoretiska förutsägelserna. Detta gör det möjligt att välja den optimala injektordesignen genom en kvantitativ bedömning av utloppskoefficienten och en kvalitativ bedömning av vinkeln och finfördelningen av injektorstrålen. Även om dessa studier baseras på starka modeller måste de jämföras med data från brännprover och senare flygdata för att kunna bedömas fullt ut, särskilt som pumptestkampanjen inte genomfördes.

High efficiency, flexibility and competitive capital costs make supercritical CO2 (sCO2) systems a promising technology for renewable power generation in a low carbon energy scenario. Recently, innovative supercritical systems have been studied in the literature and proposed by DOE-NETL (STEP project) and by a few projects in the EU Horizon 2020 (H2020) program aiming to demonstrate supercritical CO2 Brayton power plants, promising superior techno-economic features than steam cycles particularly at high temperatures. The H2020 SOLARSCO2OL project, which started in 2020, is building the first European MW-scale sCO2 demonstration plant and has been specifically tailored for Concentrating Solar Power (CSP) applications. After a detailed explanation of the modelling approach for steady and unsteady cycle simulations, this paper presents the off-design and dynamic analysis of such plant layout, which is based on a simply recuperated sCO2 cycle. The entire system model has been developed in TRANSEO environment. The part-load analysis ranged from 50% of nominal up to a 105% peak load, discussing the impact on compressor and turbine operating conditions. Full operational envelop has been determined considering cycle main constraints, such as maximum turbine inlet temperature and minimum pressure at compressor inlet. The off-design performance analysis highlights the most relevant relationships among the main part-load regulating parameters, namely molten salt mass flow rate, CO2 mass flow rate, total CO2 mass in the loop, and shaft line speed. The results show specific features of different control approaches, discussing the pros and cons of each solution, considering also its upscale towards commercial applications. In particular, the analysis shows that at 51% of load an efficiency decrease of 20% is expected. Finally, the dynamic characterization of the closed loop shows the relatively fast responsiveness of the plant to compressor speed variations, causing quick changes, QC 20230612

The concept of a vortex, characterised by the rotational or swirling motion of fluids, lacks a universally accepted definition in the field of fluid mechanics. This ambiguity hampers turbulence research and can lead to confusion and misunderstandings. This thesis addresses this issue by implementing a newly proposed vortex identification criterion, namely the triple decomposition method (TDM), on direct numerical simulation (DNS) data of a linear compressor cascade. The criterion is compared to established techniques, and two different algorithms for its implementation are introduced. Notably, a newer algorithm significantly reduces computational time compared to the original one proposed by Koláˇr (2007), addressing a key limitation of the method. The results obtained through this criterion highlight its main purpose of eliminating shear contamination, which the other methods suffer from. This development expands the potential usage of the TDM in a wider range of cases and can make it more commonly employed in the literature.

This paper examines two examples of testing activities of sub-components of a 300kN methalox first-stage rocket engine developed by Pangea Aerospace, namely, theinjectors and the cryogenic pumps. One of the difficulties of these test campaignsis to evaluate the performances of these sub-components without using cryogenicpropellants and in conditions differing from flight conditions.Two different methods were used to replace the cryogenic propellants at extreme pressures and temperatures: the pumps were tested using water to replace both propellants, and the injectors were tested using water and nitrogen to account for the different propellant phases. The correlation, similarity methods, and bench sizing were detailed for both test campaigns, but only the injector test campaign was completed and its results were analyzed.The method to emulate cryogenic fluid behavior in a pump leads to the use of a bench controlling not only pressure and mass flow but also temperature to account for the cavitation effects. Furthermore, the bench must have the capability to pressurize the water under atmospheric pressure, leading to the use of a vacuum pump. The injector test campaign produces results that closely align with theoretical predictions. This enables the selection of the optimal single-element injector design through a quantitative assessment of the discharge coefficient and a qualitative evaluation of the spray angle and atomization. Although these studies are based on strong models, they must be compared to hotfire data and later flight data to be assessed fully, all the more so that the pump test campaign was not performed., I denna rapport behandlas två exempel på provningsaktiviteter för delkomponenter av en methalox-driven 300 kN-klass raketmotor, utvecklad av Pangea Aerospace för användning på förstasteg. Delkomponenterna består av injektorerna samt dekryogena pumparna. En av svårigheterna med provkampanjerna är att utvärdera prestandan hos dessa delkomponenter utan att använda kryogena drivmedel och underförhållanden som skiljer sig från flygförhållandena. Två olika metoder användes för att imitera de kryogena drivmedlen vid extrema tryck och temperaturer. Först testades pumparna med vatten som en ersättning för de båda drivmedlen, och sedan testades injektorerna med både vatten och kväve för att ta hänsyn till de olika aggregations tillstånden. Korrelationen, likhetsmetoderna, samt provbänkstorleken utredes i detalj för bägge testkampanjer, men endast injektortestkampanjen slutfördes och dess resultat analyserades. Metoden för att efterlikna kryogena vätskors beteende i en pump leder till användning av en provbänk som inte bara reglerar tryck och massflöde utan även temperatur för att ta hänsyn till kavitations effekterna. Dessutom måste bänken ha kapacitet att trycksätta vattnet under atmosfärstryck, vilket leder till användning av en vakuumpump. Injektortestkampanjen ger resultat som ligger nära de teoretiska förutsägelserna. Detta gör det möjligt att välja den optimala injektordesignen genom en kvantitativ bedömning av utloppskoefficienten och en kvalitativ bedömning av vinkeln och finfördelningen av injektorstrålen. Även om dessa studier baseras på starka modeller måste de jämföras med data från brännprover och senare flygdata för att kunna bedömas fullt ut, särskilt som pumptestkampanjen inte genomfördes.

Im Rahmen des Auslegungsprozesses von Turbomaschinen können aerodynamisch optimale Designs oftmals nicht realisiert werden, da in der aeroelastischen Auslegung die strukturelle Integrität nicht gewährleistet ist. Problematisch sind dabei hohe Schwingungsamplituden, die beispielsweise durch selbsterregte Schwingungen (Flattern) oder zwangserregte Schwingungen (Forced Response) auftreten. Eine wichtige Einflussgröße bei der Vorhersage dieser Phänomene ist die Dämpfung. Allgemein wird angenommen, dass diese beim Fehlen von Reibkontakten normalerweise hauptsächlich aus der aerodynamischen Dämpfung besteht. In dieser Arbeit soll der Einfluss von zusätzlicher Dämpfung durch die Rotorlagerung auf die Gesamtdämpfung und auf das Schwingungsverhalten bei Forced Response untersucht werden. Dieser Einfluss kommt bei der Kopplung der Schaufelschwingungen in den Knotendurchmesser 1 und -1 mit den Rotorschwingungen zum Tragen, da die Dämpfung aus einer strukturdynamischen Interaktion dieser beiden Komponenten resultiert. Zu diesem Zweck wird eine Simulationskette aufgebaut, die die physikalischen Effekte im Betrieb bestmöglich abbildet. Die Simulationskette basiert im Wesentlichen auf einem strukturdynamischen Vollmodell des Blisk-Rotor-Verbundes und einem instationären CFD-Modell unter Nutzung der Harmonic Balance Methode zur Berücksichtigung der aeroelastischen Effekte. Zusätzlich erfolgt auf Basis einer experimentellen Modalanalyse im Stillstand eine Identifikation der Verstimmungsparameter der Beschaufelung. Alle Ergebnisse fließen in ein strukturdynamisches Modell reduzierter Ordnung ein, das das Schwingungsverhalten der Beschaufelung berechnet. Die numerischen Ergebnisse werden mit Messdaten verglichen. Dies umfasst insbesondere im Betrieb bestimmte Dämpfungen unter Nutzung eines akustischen Anregungssystems und gemessene Frequenzgänge bei Forced Response. Die numerischen Ergebnisse zeigen dabei im Rahmen der experimentellen Unsicherheiten eine sehr gute Übereinstimmung mit, During the design process of turbomachinery, it is often not possible to realize aerodynamically optimal designs due to aeroelastic constraints. The design choices are limited by possible structural failure, which can be caused by high vibration amplitudes, e.g. due to self-excited vibrations (flutter) or forced vibrations (forced response). In particular, the modal damping has an important impact on these phenomena. In the absence of frictional contacts, damping is mainly created by aerodynamics. In this work, the influence of additional damping due to the rotor bearing on the total damping and on the vibrational behavior in forced response will be investigated. This influence comes becomes relevant when blade vibrations in nodal diameters 1 and -1 couple with the rotor vibrations. This is caused by a structural dynamic interaction of these two components. For this purpose, a simulation process is set up to best represent the physical effects during operation. The simulation process is essentially based on a full structural dynamic model of the blisk-rotor assembly and an unsteady CFD model using the harmonic balance method to account for the aeroelastic effects. In addition, a mistuning identification of the blading is performed based on an experimental modal analysis at standstill. All results are incorporated into a structural dynamic reduced order model that calculates the vibrational behavior of the blading. The numerical results are compared with measurement data. In particular, this includes damping determined in operation using an acoustic excitation system and measured frequency responses due to forced response. The numerical results show very good agreement with the experimental results within the measurement uncertainty, both with respect to the damping and the mistuned frequency responses. Furthermore, the blade-rotor interaction results in significant changes of the eigenfrequencies and damping. As a consequence, damping increases by up to fifteen time

In the pursuit of reducing the climate impact of aviation, there has been an increased interest in the adoption of renewable energy technologies. Examples of revolutionary technologies include hydrogen fuel cell systems and waste heat recovery using the organic Rankine cycle. The design of viable energy conversion systems for aviation poses unique challenges in terms of efficiency, weight and size. To this end, research on small-scale turbomachinery operating at high rotational speeds is increasingly pursued in the context of, for example, fuel cell air compressors or organic Rankine cycle turbines. Such machines typically call for oil-free operation to avoid contamination of the process fluid. Gas foil bearings can prove to be an enabling technology due to their reliability, oil-free operation and compatibility with high rotational speeds. The use of gas foil bearings to support organic Rankine cycle turbines requires lubrication with complex working fluids at operating conditions near the saturated vapour line or thermodynamic critical point. Although there has been an increased interest in high-pressure gas lubrication in recent scientific literature, there is still a lack of understanding of the effects of non-ideal compressible flows on the performance of (gas foil) journal bearings. In order to further address this knowledge gap, this work focuses on the modelling of such bearings lubricated with dense fluids made by complex molecules like those adopted for waste heat recovery at high temperatures in aviation. The compressible Reynolds equation governing the thin-film flow within the bearing is discretized using a finite difference method. The solution to the non-linear problem is obtained using a relaxation method in which a thermodynamic software program updates the non-ideal thermodynamic state properties after each iteration. The load-carrying capacity of the bearing is obtained by integrating the resulting steady-state pressure field ar, Aerospace Engineering

Im Rahmen des Auslegungsprozesses von Turbomaschinen können aerodynamisch optimale Designs oftmals nicht realisiert werden, da in der aeroelastischen Auslegung die strukturelle Integrität nicht gewährleistet ist. Problematisch sind dabei hohe Schwingungsamplituden, die beispielsweise durch selbsterregte Schwingungen (Flattern) oder zwangserregte Schwingungen (Forced Response) auftreten. Eine wichtige Einflussgröße bei der Vorhersage dieser Phänomene ist die Dämpfung. Allgemein wird angenommen, dass diese beim Fehlen von Reibkontakten normalerweise hauptsächlich aus der aerodynamischen Dämpfung besteht. In dieser Arbeit soll der Einfluss von zusätzlicher Dämpfung durch die Rotorlagerung auf die Gesamtdämpfung und auf das Schwingungsverhalten bei Forced Response untersucht werden. Dieser Einfluss kommt bei der Kopplung der Schaufelschwingungen in den Knotendurchmesser 1 und -1 mit den Rotorschwingungen zum Tragen, da die Dämpfung aus einer strukturdynamischen Interaktion dieser beiden Komponenten resultiert. Zu diesem Zweck wird eine Simulationskette aufgebaut, die die physikalischen Effekte im Betrieb bestmöglich abbildet. Die Simulationskette basiert im Wesentlichen auf einem strukturdynamischen Vollmodell des Blisk-Rotor-Verbundes und einem instationären CFD-Modell unter Nutzung der Harmonic Balance Methode zur Berücksichtigung der aeroelastischen Effekte. Zusätzlich erfolgt auf Basis einer experimentellen Modalanalyse im Stillstand eine Identifikation der Verstimmungsparameter der Beschaufelung. Alle Ergebnisse fließen in ein strukturdynamisches Modell reduzierter Ordnung ein, das das Schwingungsverhalten der Beschaufelung berechnet. Die numerischen Ergebnisse werden mit Messdaten verglichen. Dies umfasst insbesondere im Betrieb bestimmte Dämpfungen unter Nutzung eines akustischen Anregungssystems und gemessene Frequenzgänge bei Forced Response. Die numerischen Ergebnisse zeigen dabei im Rahmen der experimentellen Unsicherheiten eine sehr gute Übereinstimmung mit, During the design process of turbomachinery, it is often not possible to realize aerodynamically optimal designs due to aeroelastic constraints. The design choices are limited by possible structural failure, which can be caused by high vibration amplitudes, e.g. due to self-excited vibrations (flutter) or forced vibrations (forced response). In particular, the modal damping has an important impact on these phenomena. In the absence of frictional contacts, damping is mainly created by aerodynamics. In this work, the influence of additional damping due to the rotor bearing on the total damping and on the vibrational behavior in forced response will be investigated. This influence comes becomes relevant when blade vibrations in nodal diameters 1 and -1 couple with the rotor vibrations. This is caused by a structural dynamic interaction of these two components. For this purpose, a simulation process is set up to best represent the physical effects during operation. The simulation process is essentially based on a full structural dynamic model of the blisk-rotor assembly and an unsteady CFD model using the harmonic balance method to account for the aeroelastic effects. In addition, a mistuning identification of the blading is performed based on an experimental modal analysis at standstill. All results are incorporated into a structural dynamic reduced order model that calculates the vibrational behavior of the blading. The numerical results are compared with measurement data. In particular, this includes damping determined in operation using an acoustic excitation system and measured frequency responses due to forced response. The numerical results show very good agreement with the experimental results within the measurement uncertainty, both with respect to the damping and the mistuned frequency responses. Furthermore, the blade-rotor interaction results in significant changes of the eigenfrequencies and damping. As a consequence, damping increases by up to fifteen time

This document contains the final Master Thesis Report to obtain the Master of Science on Aerospace Engineering (Flight Performance & Propulsion - Propulsion & Power) at the Delft University of Technology. The research work focuses on characterizing the interaction of a radial inlet turbine with a downstream diffuser through the size of the rotor tip gaps. In the implementation of power turbines it is common to add a diffuser downstream of it to lower the rotor exhaust pressure and thus increase power extraction for the same inlet conditions. However, diffusersare bulky and take a lot of space in the assembly. This lowers the power density of the machine, increases installation weight in transport applications, and installation costs in ground based operations. In the quest to obtain compact diffusers, researchers noticed that the non-dimensional static pressure recovery (Cp) of this device was higher when operating downstream of a turbine than with uniform inlet conditions. The publications in this field are relatively scarce, and thus there is a knowledge gap with immediate practical application. Some researchers have focused on the interaction of turbine vortical structures with the boundary layer of the diffuser. They have found out that under this conditions the boundary layer can support steeper pressure gradients without detaching. This is only applicable in very steep diffusers that would stall in isolation. Notably, all the publications in this field deal with axial machines, and as the text will show the picture changes considerably when applying the theory to radial turbines. This work studies another side of the problem. The text will focus on stable diffusers, and thus there is no boundary layer that needs reinforcement. Turbine rotor tip gaps generate an increase of entropy and reduce turbine power generation. However, these gaps also cast powerful vortexes that affect the diffuser flowfield. This project will study th, Aerospace Engineering | Flight Performance and Propulsion

The use of CFD-based optimizations is becoming a standard for turbomachinery design. Although the use of such optimizations can lead to great improvements of the machine performances, there are still several shortcomings in the common design procedure of turbomachines. In fact, this entails the optimization of the component shape, and only a retrospective check on manufacturing feasibility and structural viability. This might lead to several design iterations and lot of time wasted. This thesis project aims at developing a multidisciplinary optimization method where the structural behaviour of the part can be checked already in the first part of the design process. This is done by using the "cold" design as first guess of the optimization, and by performing a fluid-structure interaction to predict the deformations of the part, and simultaneously investigating the behaviour of the flow field, in order to obtain the performances achieved by the operating "hot" design., Aerospace Engineering

Modal parameter identification can be a valuable tool in mechanical engineering to predict vibrational behaviour and avoid machine damage during operation. Operational modal analysis is an output-only identification tool motivated by the structural identification of civil engineering structures, which are excited by ambient conditions. This technique is increasingly applied in mechanical engineering in order to characterise the system behaviour during operation as modal parameters can vary under operating conditions. The following study investigates the application of operational modal analysis on an axial compressor under operating conditions. Since the modal parameters of the system change depending on the life history and during the operation of the system, a corresponding data analysis might allow us to identify the present status of the system. Eigenfrequencies and eigenvectors are studied for the use of structural health monitoring approaches. According to the analysis, eigenfrequencies represent robust parameters for the studied purpose. Eigenvectors are sensitive to damages but need further investigation, especially for rotating machinery. This study will help the user to set up a virtual model, which describes the system behaviour for different boundary conditions. This in turn, will provide an accurate prediction of the vibrational behaviour in order to assure a safe operation.

Modal parameter identification can be a valuable tool in mechanical engineering to predict vibrational behaviour and avoid machine damage during operation. Operational modal analysis is an output-only identification tool motivated by the structural identification of civil engineering structures, which are excited by ambient conditions. This technique is increasingly applied in mechanical engineering in order to characterise the system behaviour during operation as modal parameters can vary under operating conditions. The following study investigates the application of operational modal analysis on an axial compressor under operating conditions. Since the modal parameters of the system change depending on the life history and during the operation of the system, a corresponding data analysis might allow us to identify the present status of the system. Eigenfrequencies and eigenvectors are studied for the use of structural health monitoring approaches. According to the analysis, eigenfrequencies represent robust parameters for the studied purpose. Eigenvectors are sensitive to damages but need further investigation, especially for rotating machinery. This study will help the user to set up a virtual model, which describes the system behaviour for different boundary conditions. This in turn, will provide an accurate prediction of the vibrational behaviour in order to assure a safe operation.

Conventional centralized power generation is increasingly transforming into a more distributed structure. The periodic power production that is created by the renewable production unit generates the need for small-scale heat and power units. One of the promising technologies which can assist flexible power grid is micro Gas Turbines (mGTs). Such engines are competent candidates for small-scale Combined Heat and Power (CHP). mGTs, as compensators for the demand fluctuations, are required to work on transient and part-load conditions, creating new research challenges. A complete characterization of their dynamic behavior through a real-time simulation tool is necessary to establish effective control systems. Moreover, the energy transition requires the conversion of conventional mGTs to more sophisticated high-efficient cycles with the addition of extra components (saturation unit, aftercooler, etc). Consequently, a modular and computationally fast real-time tool offers an asset in the development of future cycles based on the mGT concept. This paper presents the development of a numerical in-house tool implemented in Python programming language for the performance prediction of the mGT. The fundamental target of our work is to achieve high fidelity of the simulated dynamic responses. The key benefit of this tool is the low complexity component modules. The model is validated with experimental results from the VUB T100 test rig. The code reproduces the experimental data well during steady-state and transient operations as the key cycle parameters present a deviation from the measurements within the range of 1.5%.

A characteristic of radial turbines for turbocharger applications subject to pulsating flow is the deviation of the turbine performance compared with corresponding continuous flow conditions, typically associated with gas-stand experiments. The performance deviations under pulsating flow generate a hysteresis loop that encloses the performance line obtained in gas-stand conditions and their intensity is demonstrated to grow with increasing pulse amplitude and frequency. Predicting the performance deviations is of great interest to improve the predictive capabilities of reduced-order models and enhance engine-turbocharger matching. In this work, the performance response of a turbocharger radial turbine is studied with respect to variations of the normalized pulse amplitude (between 0.4 and 1.6) and the pulse frequency (between 20Hz and 100Hz). Results show that the hysteresis loop expands with increasing pulse amplitude and frequency, so that the turbine cannot be treated as a quasi-steady device. The characteristic trends of the turbine performance are also highlighted with respect to pulse amplitude and frequency variations. The expansion ratio is registered to improve by +4.0% with increasing pulse amplitude and decrease by -1.3% with increasing pulse frequency. An opposite trend is otherwise registered for the isentropic efficiency, which decreases by -6.5% for increasing pulse amplitude and increases by +6.5% for increasing pulse frequency. Finally, through a simple model, the deviations of the turbine performance from quasi-steady to pulsating flow conditions are demonstrated to depend on the time derivative of the pressure pulse and the residence time of the fluid particle rather than pulse amplitude and frequency., QC 20221206, CCGEx

This work presents the development and application of a machine learning model to predict the unsteady performance of a turbocharger radial turbine subject to on-engine pulsating flow conditions. The model proposed, based on a fully connected neural network, predicts the instantaneous turbine torque and circumferentiallyaveraged relative inflow angle when given, as only inputs, the total pressure and temperature pulses and the time derivative of the total pressure pulse upstream of the turbine. The training data set for the model is obtained from an experimentally-validated Reynolds-averaged Navier-Stokes model and consists of various operating conditions characterized by different pulse amplitudes and frequencies. Heat transfer effects are neglected by the use of adiabatic boundary conditions while the rotational speed of the rotor is otherwise maintained fixed. Based on the results obtained, the model is shown capable of accurately predicting the turbine torque and local properties of the flow, such as the relative inflow angle, with a high degree of accuracy (coefficient of determination larger than 0.98). At first, the model is tested for both interpolation and extrapolation conditions. Given a training data set constituted by only three pulses characterized by different amplitudes, the model accurately predicts the turbine performance both for conditions inside and outside the range of amplitudes of the training data set. Lastly, the model is trained with a larger data set, including both variations of the pulse amplitude and frequency, in order to predict the performance of the turbine subject to a more general pulse shape. The error indicators show an improvement with respect to the extrapolation case due to the larger size of the training data set, showing also a great capability of the model to predict the unsteady performance of the turbine for a more general pulse shape. The model represents a fast and efficient approach for predicting the unsteady turbin, Not duplicate with DiVA 1696820QC 20221031

Supercritical CO2 (sCO2) power cycles have been identified as technology enablers for increasing the cost-competitiveness of Concentrating Solar Power (CSP) plants. Compared to steam cycles, sCO2 cycles have the advantage of allowing higher inlet turbine temperatures, while also deploying turbomachinery that can be a ten-fold more compact. Ongoing research in CSP focuses mainly in developing new receiver and storage concepts able to withstand such required higher temperatures, alongside new heat exchangers that enable coupling to a sCO2 cycle. Meanwhile, advancements in sCO2 turbomachinery have taken place in research projects aimed at investigating the technical feasibility of the cycle, including the optimized design of its individual components and new cycle configurations. Among these, only few focus in demonstrating a full-integrated system, including cycle control and dynamics, and only two worldwide have started plans for MW-scale pilots, none of them in Europe. The EU-funded SOLARSCO2OL project aims at demonstrating a first-of-a-k ind 2 MW gross simple-recuperated sCO2 Brayton cycle driven by heat provided by molten salt s similar to those deployed in commercial CSP plants, which are able to operate at temperatures of up to 580°C. This paper introduces the project objectives and implementation plan, to then focus primarily on the results derived from the first year in specific relation to the conceptual design of each of 2 MW scale power cycle and its k ey components, including also the proposed integration and operational regimes, expected thermod ynamic performance at nominal point, and up-scaling considerations., QC 20230614

High efficiency, flexibility and competitive capital costs make supercritical CO2 (sCO2) systems a promising technology for renewable power generation in a low carbon energy scenario. Recently, innovative supercritical systems have been studied in the literature and proposed by DOE-NETL (STEP project) and a few projects in the EU Horizon 2020 program aiming to demonstrate supercritical CO2 Brayton power plants, promising superior techno-economic features than steam cycles particularly at high temperatures. The H2020 SOLARSCO2OL project1, which started in 2020, is building the first European MW-scale sCO2 demonstration plant and has been specifically tailored for Concentrating Solar Power (CSP) applications. This paper presents the first offdesign analysis of such a demonstrator, which is based on a simply recuperated sCO2 cycle. The part-load analysis ranged from 50% of nominal up to a 105% peak load, discussing the impact on compressor and turbine operating conditions. The whole system dynamic model has been developed in TRANSEO MATLAB® environment. Full operational envelop has been determined considering cycle main constraints, such as maximum turbine inlet temperature and minimum pressure at compressor inlet. The off-design performance analysis highlights the most relevant relationships among the main part-load regulating parameters, namely mass flow rate, total mass in the loop, and available heat source. The results show specific features of different control approaches, discussing the pros and cons of each solution, considering also its upscale towards commercial applications. In particular, the analysis shows that at 51% of load an efficiency decrease of 20% is expected., QC 20230614

Experimental and numerical, are presented in the transonic linear cascade (TLC) at KTH. Numerical results are recovered by SST turbulence model with a reattachment modification (RM) from commercial software Ansys CFX. This paper aims to compare the current numerical methods as a step towards producing open data for validation purposes. The operational point is representative of an open source virtual compressor (VINK) operating near stall at part speed, with an induced leading edge separation bubble at an inlet Mach number of 0.81. Steady-state results consists of Laser-2-Focus anemometer (L2F), blade loading, flow visualization and five-hole probe measurements. Steady-state numerical results indicate an over prediction of low momentum regions in the passages and under prediction of a separation bubble. The cascade operates in the influence coefficient domain, where the central blade vibrates in its first natural mode shape with 0.69 reduced frequency. Unsteady pressure coefficients display an amplitude discrepancy between methods. Numerically, the unsteady pressure content at the measurement plane (85% span) is dominated by the oscillation of the tip leakage vortex, which is not observed from experimental data. Despite a qualitative mismatch with the unsteady pressure amplitude, the phase- lag shows good agreement between both methods, which is of high relevance when predicting the aerodynamic damping., QC 20230619, ADiSS

Experimental and numerical, are presented in the transonic linear cascade (TLC) at KTH. Numerical results are recovered by SST turbulence model with a reattachment modification (RM) from commercial software Ansys CFX. This paper aims to compare the current numerical methods as a step towards producing open data for validation purposes. The operational point is representative of an open source virtual compressor (VINK) operating near stall at part speed, with an induced leading edge separation bubble at an inlet Mach number of 0.81. Steady-state results consists of Laser-2-Focus anemometer (L2F), blade loading, flow visualization and five-hole probe measurements. Steady-state numerical results indicate an over prediction of low momentum regions in the passages and under prediction of a separation bubble. The cascade operates in the influence coefficient domain, where the central blade vibrates in its first natural mode shape with 0.69 reduced frequency. Unsteady pressure coefficients display an amplitude discrepancy between methods. Numerically, the unsteady pressure content at the measurement plane (85% span) is dominated by the oscillation of the tip leakage vortex, which is not observed from experimental data. Despite a qualitative mismatch with the unsteady pressure amplitude, the phase- lag shows good agreement between both methods, which is of high relevance when predicting the aerodynamic damping., QC 20230619, ADiSS

Experimental and numerical, are presented in the transonic linear cascade (TLC) at KTH. Numerical results are recovered by SST turbulence model with a reattachment modification (RM) from commercial software Ansys CFX. This paper aims to compare the current numerical methods as a step towards producing open data for validation purposes. The operational point is representative of an open source virtual compressor (VINK) operating near stall at part speed, with an induced leading edge separation bubble at an inlet Mach number of 0.81. Steady-state results consists of Laser-2-Focus anemometer (L2F), blade loading, flow visualization and five-hole probe measurements. Steady-state numerical results indicate an over prediction of low momentum regions in the passages and under prediction of a separation bubble. The cascade operates in the influence coefficient domain, where the central blade vibrates in its first natural mode shape with 0.69 reduced frequency. Unsteady pressure coefficients display an amplitude discrepancy between methods. Numerically, the unsteady pressure content at the measurement plane (85% span) is dominated by the oscillation of the tip leakage vortex, which is not observed from experimental data. Despite a qualitative mismatch with the unsteady pressure amplitude, the phase- lag shows good agreement between both methods, which is of high relevance when predicting the aerodynamic damping., QC 20230619, ADiSS

Experimental and numerical, are presented in the transonic linear cascade (TLC) at KTH. Numerical results are recovered by SST turbulence model with a reattachment modification (RM) from commercial software Ansys CFX. This paper aims to compare the current numerical methods as a step towards producing open data for validation purposes. The operational point is representative of an open source virtual compressor (VINK) operating near stall at part speed, with an induced leading edge separation bubble at an inlet Mach number of 0.81. Steady-state results consists of Laser-2-Focus anemometer (L2F), blade loading, flow visualization and five-hole probe measurements. Steady-state numerical results indicate an over prediction of low momentum regions in the passages and under prediction of a separation bubble. The cascade operates in the influence coefficient domain, where the central blade vibrates in its first natural mode shape with 0.69 reduced frequency. Unsteady pressure coefficients display an amplitude discrepancy between methods. Numerically, the unsteady pressure content at the measurement plane (85% span) is dominated by the oscillation of the tip leakage vortex, which is not observed from experimental data. Despite a qualitative mismatch with the unsteady pressure amplitude, the phase- lag shows good agreement between both methods, which is of high relevance when predicting the aerodynamic damping., QC 20230619, ADiSS

Experimental and numerical, are presented in the transonic linear cascade (TLC) at KTH. Numerical results are recovered by SST turbulence model with a reattachment modification (RM) from commercial software Ansys CFX. This paper aims to compare the current numerical methods as a step towards producing open data for validation purposes. The operational point is representative of an open source virtual compressor (VINK) operating near stall at part speed, with an induced leading edge separation bubble at an inlet Mach number of 0.81. Steady-state results consists of Laser-2-Focus anemometer (L2F), blade loading, flow visualization and five-hole probe measurements. Steady-state numerical results indicate an over prediction of low momentum regions in the passages and under prediction of a separation bubble. The cascade operates in the influence coefficient domain, where the central blade vibrates in its first natural mode shape with 0.69 reduced frequency. Unsteady pressure coefficients display an amplitude discrepancy between methods. Numerically, the unsteady pressure content at the measurement plane (85% span) is dominated by the oscillation of the tip leakage vortex, which is not observed from experimental data. Despite a qualitative mismatch with the unsteady pressure amplitude, the phase- lag shows good agreement between both methods, which is of high relevance when predicting the aerodynamic damping., QC 20230619, ADiSS

This work sets out the creation, verification and demonstration of an automated end-to-end tool for the multi-point fluid-dynamic optimization of turbomachinery. Taking into account multiple operating conditions during optimization aims to benefit the overall performance of turbomachines which are characterized by off-design operation and to produce more robust designs with respect to deviations in operating conditions. The feasibility and effectiveness of the tool is demonstrated by a two-point fluid-dynamic optimization of a two-dimensional Aachen turbine stator cascade, performed on the High-Performance Computing cluster of the TU Delft. By utilizing the stochastic NSGA2 optimization algorithm, the numerically noisy problem is successfully optimized. The entropy generation of the blade is reduced at both nominal and off-design operating condition by an average of 7.57%, while satisfying a constraint on the flow turning when passing through the stator cascade. Additionally, a numerical noise analysis shows that disregarding the most noisy design variables increases the probability of obtaining an improved design., Aerospace Engineering

[ES] El objetivo del proyecto es obtener una solución espectral de la ecuación de lubricación de películas de Reynolds para cojinetes hidrostáticos de longitud finita como una solución exacta de una expansión de series infinitas. Para los cojinetes hidrodinámicos, debido a las simetrías intrínsecas de la geometría del cojinete y el campo de flujo, la PDE cuasi-lineal 2D de segundo orden relevante en el dominio rectangular con BCs periódicas y homogéneas se resolvió mediante autofunciones sinusoidales adecuadas. Sin embargo, en el caso de los cojinetes de deslizamiento hidrostáticos con compensación de orificio con inyección distribuida, ha sido necesario modificar las autofunciones para adaptarse a las nuevas BCS que definen la caída de presión en la inyección. La solución espectral se ha implementado en un código Matlab y se ha utilizado para calcular las prestaciones de cojinetes deslizantes con una relación de aspecto lejos de las aproximaciones típicas de cojinetes "largos" y "cortos"., [EN] The objective of the project is to obtain a spectral solution of the Reynolds¿film lubrication equation for finite length hydrostatic journal bearing as an exact solution for infinite series expansion. For hydrodynamic journal bearings, due to the intrinsic symmetries of the bearing geometry and flow field, the relevant 2nd order 2D quasi-linear PDE in the rectangular domain with periodic and homogenous BCs was solved through suitable sinusoidal eigenfunctions. However, in the case of hydrostatic orifice-compensated journal bearings with distributed injection, it has been necessary to modify the eigenfunctions to accommodate the new BCs that define the pressure drop at the injection. The spectral solution has been implemented into a Matlab code and used to compute the performance of journal bearings with aspect ratio far from the typical approximations of ¿long¿ and ¿short¿ bearing.

[ES] En el trabajo se lleva a cabo el desarrollo, análisis y comprobación de la digitalización del escalonamiento de un compresor axial transónico de baja relación de aspecto y alta relación de compresión. Se trata de la etapa 37 diseñada y ensayada por la NASA. A pesar de que se emplea como referencia en numerosos trabajos, no existe una geometría CAD autoritativa de la misma, ni una metodología abierta y detallada para su digitalización a partir de los informes originales de la NASA. En el proyecto, se comienza por la digitalización de la geometría, tanto del rotor como del estator. En esta parte se destacan los principales fallos encontrados en el proceso. Seguidamente la geometría será tratada por medio del programa Ansys TurboGrid para generar automáticamente una malla estructurada y configurable a lo largo del volumen de control, lo que permitirá realizar simulaciones numéricas previas de las características aerodinámicas de la etapa de compresor., [EN] In this work, the development, analysis and testing of the digitization of a low aspect ratio, high compression ratio transonic axial compressor stage is carried out. It is the stage 37 designed and tested by NASA. Although it is used as a reference in several works, there is no authoritative CAD geometry of it, nor an open and detailed methodology for its digitization from the original NASA reports. The project starts with the digitization of the geometry of both the rotor and the stator. In this part, the main issues found in the process are highlighted. Then the geometry is treated by means of Ansys TurboGrid to automatically generate a structured and configurable mesh along the control volume, which will allow to perform previous numerical simulations of the aerodynamic characteristics of the compressor stage.

[ES] El objetivo del proyecto es obtener una solución espectral de la ecuación de lubricación de películas de Reynolds para cojinetes hidrostáticos de longitud finita como una solución exacta de una expansión de series infinitas. Para los cojinetes hidrodinámicos, debido a las simetrías intrínsecas de la geometría del cojinete y el campo de flujo, la PDE cuasi-lineal 2D de segundo orden relevante en el dominio rectangular con BCs periódicas y homogéneas se resolvió mediante autofunciones sinusoidales adecuadas. Sin embargo, en el caso de los cojinetes de deslizamiento hidrostáticos con compensación de orificio con inyección distribuida, ha sido necesario modificar las autofunciones para adaptarse a las nuevas BCS que definen la caída de presión en la inyección. La solución espectral se ha implementado en un código Matlab y se ha utilizado para calcular las prestaciones de cojinetes deslizantes con una relación de aspecto lejos de las aproximaciones típicas de cojinetes "largos" y "cortos"., [EN] The objective of the project is to obtain a spectral solution of the Reynolds¿film lubrication equation for finite length hydrostatic journal bearing as an exact solution for infinite series expansion. For hydrodynamic journal bearings, due to the intrinsic symmetries of the bearing geometry and flow field, the relevant 2nd order 2D quasi-linear PDE in the rectangular domain with periodic and homogenous BCs was solved through suitable sinusoidal eigenfunctions. However, in the case of hydrostatic orifice-compensated journal bearings with distributed injection, it has been necessary to modify the eigenfunctions to accommodate the new BCs that define the pressure drop at the injection. The spectral solution has been implemented into a Matlab code and used to compute the performance of journal bearings with aspect ratio far from the typical approximations of ¿long¿ and ¿short¿ bearing.

[ES] En el trabajo se lleva a cabo el desarrollo, análisis y comprobación de la digitalización del escalonamiento de un compresor axial transónico de baja relación de aspecto y alta relación de compresión. Se trata de la etapa 37 diseñada y ensayada por la NASA. A pesar de que se emplea como referencia en numerosos trabajos, no existe una geometría CAD autoritativa de la misma, ni una metodología abierta y detallada para su digitalización a partir de los informes originales de la NASA. En el proyecto, se comienza por la digitalización de la geometría, tanto del rotor como del estator. En esta parte se destacan los principales fallos encontrados en el proceso. Seguidamente la geometría será tratada por medio del programa Ansys TurboGrid para generar automáticamente una malla estructurada y configurable a lo largo del volumen de control, lo que permitirá realizar simulaciones numéricas previas de las características aerodinámicas de la etapa de compresor., [EN] In this work, the development, analysis and testing of the digitization of a low aspect ratio, high compression ratio transonic axial compressor stage is carried out. It is the stage 37 designed and tested by NASA. Although it is used as a reference in several works, there is no authoritative CAD geometry of it, nor an open and detailed methodology for its digitization from the original NASA reports. The project starts with the digitization of the geometry of both the rotor and the stator. In this part, the main issues found in the process are highlighted. Then the geometry is treated by means of Ansys TurboGrid to automatically generate a structured and configurable mesh along the control volume, which will allow to perform previous numerical simulations of the aerodynamic characteristics of the compressor stage.

In the battle against climate change, humankind needs to develop alternative energy systems if it wants to survive on this planet. Fossil fuels, polluting the air with CO2, must make way for renewable sources so that climate change is put to a stop. Several new energy initiatives based on renewable sources are deployed worldwide, these however are mostly for electricity generation. There are elatively few zero emission alternatives developed for the energy demand from the transport sector, therefore, new small scale energy systems need to be developed in order to achieve the goals stated in the Paris agreement. The Hydrogen Roadmap” is a vital part of the European Union in achieving the Paris climate agreement, which uses hydrogen for future energy generation. Gas turbines, steam turbines and fuel cell applications are investigated thoroughly for small scale energy systems throughout the years. Fewer research is conducted about the integration of these three energy technologies and specially sparse research has been conducted in the area of pure hydrogen oxygen combustion for these energy systems, resulting in opportunities for development. This report introduces an alternative small scale power system suited for the newest inland shipping vessels. It proposes a basic design for a 3 MW SOFC integrated hydrogen oxygen fired combined power cycle, feasible within 10 to 20 years of research and development. First, the theoretical background for the research is elaborated covering the thermodynamics of traditional power cycles, exergy analysis theory and zero emission cycles such as hydrogen oxygen fuelled power cycles. The electrochemical research containing the fuel cell operating specifics and the advantages of integrating fuel cell stacks in power cycles is introduced next. The theoretical background ends with an elaboration on the preliminary design steps for power cycle components regarding turbomachinery and heat exchange equipment. After the relevant subjects reg, Mechanical Engineering | Energy and Process Technology

In this energy transition era, turbocharging is still an important technology for the automotive industry to reduce fuel consumption and lower emissions in its vehicles. This importance can be seen from both conventional fossil-fuel powertrains, and emerging applications, such as increased utilization of biofuels along with hydrogen fuel cells. For automotive turbochargers, the turbine has mainly two alternative types, i.e., mixed flow turbines (MFTs) and radial flow turbines (RFTs). These devices are mature and commercially available yet still have significant potential for improvement towards ensuring higher performance, more robust operation, and lower cost. With this in mind the overall aim of this study is to improve the aerodynamic design and the aeromechanical analysis methods for MFTs and RFTs. Specifically, the investigation covers three research topics: meanline method, stator tilting endwall design, and forced response analysis. A meanline method tool is newly developed to predict the performance curves. For RFTs, the results present a generally good agreement between the predicted performance and experimental data. However, for MFTs, two limitations of loss models used in the meanline method have been identified: spanwise variation of incidence at the rotor inlet is neglected; and performance variations at different speeds cannot be captured by the investigated passage loss models. To overcome the first limitation, a multi-section incidence loss model is proposed. For the second limitation, more research work is suggested to investigate the effect of mixed-flow features at the MFT rotor inlet. As a contribution to investigate the mixed-flow feature at the MFT rotor inlet, different stator tilting endwall designs are numerically evaluated with computational fluid dynamics (CFD) tools. An MFT with well-documented experimental data is selected as the baseline and used to validate the CFD method. Performance improvement has been seen from those design, Under den pågående energiomställningen i samhället är turboladdning fortfarande en viktig teknik för fordonsindustrin för att minska bränsleförbrukningen och sänka utsläppen för sina fordon. Turboladdarens betydelsefullhet kan ses inom både konventionella drivsystem för fossila bränslen och framväxande applikationer, såsom ökat utnyttjande av biodrivmedel till-sammans med vätgasbränsleceller. För turboladdare till bilar har turbinen huvudsakligen två alternativa typer, dvs. mixade inflödesturbiner (MFT) och radiella inflödesturbiner (RFT). Dessa enheter är mogna och kommersiellt tillgängliga men ändå finns det en betydande förbättringspotential mot högre prestanda, mer robust drift och lägre kostnad. Med detta i åtanke är det övergripande syftet med denna studie att förbättra den aero-dynamiska designen och de aeromekaniska analysmetoderna för MFT och RFT. Specifika områden som behandlas är: aero-dynamisk mittsnittsanalys, vinklade statorändväggar och påt-vingad respons (forced respons). Ett verktyg för mittsnittsanalys har nyligen utvecklats för att förutsäga prestandakurvor. För RFT:er visar resultaten en generellt god överensstämmelse mellan den förutsagda prest-andan och presenterade experimentella data. För MFT:er har dock två begränsningar av förlustmodeller som används i mittsnittsanlys identifierats: radiell variation av inloppsvinkeln tas inte hänsyn till och prestationsvariationer vid olika hastigheter kan inte fångas av de undersökta rotorpassage-förlustmodellerna. För att övervinna den första begränsningen föreslås en flersektionsmodell för incidensförlust vid inloppet. För den andra begränsningen föreslås mer forskningsarbete för att undersöka effekten av mixat flöde vid MFT-rotorinloppet. Som ett bidrag för att utreda egenskaper för mixat flöde vid MFT-rotorinloppet utvärderas olika vinklade statorändväggs-designer numeriskt med CFD-verktyg (computational fluid dynamics). En MFT med väldokumenterade experimentella data väljs ut som basfall och används

The experimental characterization of turbulence is a challenging task, as demanding measurements are required in terms of quality and resolution. This task is even more challenging in high speed and complex flows like turbomachinery flows, due to the limitations of measurement techniques in such environments. In this context, the goal of this thesis is to develop a series of methods for improved turbulence measurements in challenging flow environments, typical of industrial applications. The focus is placed on intrusive measurement techniques which are of wide application in both industry and academia: Constant Temperature Hot Wire Anemometry and fast response pressure probes. The aforementioned techniques have been analyzed in terms of calibration, application and post-processing methods with the aim of reducing measurement errors. Particular focus has been placed on the techniques’ dynamic response. The development of an uncertainty quantification methodology for turbulence measurements is another main contribution in this work. It takes into account both the measurement uncertainty and the statistical uncertainty budgets and it can provide the evaluation of confidence intervals for all quantities of interest. Finally, two test cases are presented, showcasing the implementation of some of the developed concepts in a practical application and demonstrating the performance of turbulence measurements in a complex environment, also in terms of data reduction and processing methodologies., (FSA - Sciences de l'ingénieur) -- UCL, 2021

Psychoacoustic studies show that the level of perceived annoyance with respect to noise emitted by aircrafts engine positively depends on the sound pressure level of the tonal components in the frequency spectrum. Acoustic modes generated by the rotation of the rotor and the periodic interaction of the stationary and rotating blades in the turbomachinery parts of the aircraft engine are the main contributors to the emitted tonal noise. In order to develop mitigation measures for these modal sound fields, experimental investigations are carried out on turbomachinery test rigs. For high quality research data, similarity between measurements has to be accomplished, as even minor changes to reference conditions might impair the significance of measurements. For time-harmonic sound propagation in an inviscid and ideal flow, the Helmholtz number and the Mach number establish similarity conditions. This work addresses the establishment of similarity of modal sound propagation on test rigs where equality of the Mach number and / or the Helmholtz number cannot be met reliably between measurements. The investigation focuses on individual acoustic modes propagating in a circular duct carrying an axial uniform flow. Experimental investigations are carried out on a low-pressure air turbine test rig. The test rig is equipped with a so-called sound generator for the controlled excitation of acoustic modes of arbitrary order and at specific frequencies. Similarity of the propagation of excited modes is evaluated by analyzing the modal response function. Based on an analytical analysis of the collected measurement data and a post-hoc scaling approach, it is shown that the axial angle of the group velocity vector is a suitable parameter to establish partial similarity with respect to modal sound propagation in cases where similarity of the Helmholtz number and / or the Mach number cannot be achieved. A similarity relation between the three parameters is derived. A sensitivity analysi, Psychoakustische Studien zeigen, dass die empfundene Belästigung durch Fluglärm von dem Anteil der tonalen Komponenten im emittierten Frequenzspektrum des Triebwerks abhängig ist. Durch den Rotor und die Interaktion von rotierenden und stehenden Schaufeln im Triebwerk werden modale Schallfelder, so genannte akustisch Moden, generiert, welche als diskrete Frequenzen im abgestrahlten Spektrum auftreten. Experimentelle Versuche an Triebwerkskomponenten dienen der Entwicklung von Maßnahmen zur Reduzierung dieser modalen Anteile. Die Qualität der Messdaten ist dabei maßgeblich von der Einhaltung der Ähnlichkeit zwischen den einzelnen Messungen abhängig, da bereits minimale Änderungen in den Messbedingungen zu unterschiedlichen Ergebnissen führen können. Für die in dieser Arbeit betrachtete harmonische Schallausbreitung in einem angenommenen idealen nicht-viskosen Fluid, sind die Helmholtz-Zahl und die Mach-Zahl die bestimmenden Ähnlichkeitsparameter. In dieser Arbeit wird eine Methode zur Einhaltung von Ähnlichkeit in Bezug auf die modale Schallausbreitung vorgestellt. Die Methode konzentriert sich auf Prüfstande, bei denen bei veränderten Eintrittsbedingungen die Helmholtz-Zahl und die Mach-Zahl zwischen zwei Messungen nicht zuverlässig konstant gehalten werden können. Der Fokus liegt dabei auf der Ausbreitung einzelner Moden in einem axial durchströmten Rohr. Experimentelle Untersuchungen werden auf einem Niederdruck- Luftturbinenprüfstand durchgeführt. Im Eintritt ist ein Schallgenerator eingebaut, der die Anregung spezifischer akustischer Moden bei ausgewählten Frequenzen ermöglicht. Die Ähnlichkeit zwischen Messungen wird anhand der modalen Antwortfunktion bestimmt. Analytische Betrachtungen und eine nachträglich durchgeführte Skalierung der Messergebnisse zeigen, dass der Winkel zwischen dem modalen Gruppengeschwindigkeitsvektor und der Rohrachse geeignet ist, partielle Ähnlichkeit in Bezug auf die modale Schallausbreitung herzustellen. Eine Analyse der Ähnlichkeit

In this energy transition era, turbocharging is still an important technology for the automotive industry to reduce fuel consumption and lower emissions in its vehicles. This importance can be seen from both conventional fossil-fuel powertrains, and emerging applications, such as increased utilization of biofuels along with hydrogen fuel cells. For automotive turbochargers, the turbine has mainly two alternative types, i.e., mixed flow turbines (MFTs) and radial flow turbines (RFTs). These devices are mature and commercially available yet still have significant potential for improvement towards ensuring higher performance, more robust operation, and lower cost. With this in mind the overall aim of this study is to improve the aerodynamic design and the aeromechanical analysis methods for MFTs and RFTs. Specifically, the investigation covers three research topics: meanline method, stator tilting endwall design, and forced response analysis. A meanline method tool is newly developed to predict the performance curves. For RFTs, the results present a generally good agreement between the predicted performance and experimental data. However, for MFTs, two limitations of loss models used in the meanline method have been identified: spanwise variation of incidence at the rotor inlet is neglected; and performance variations at different speeds cannot be captured by the investigated passage loss models. To overcome the first limitation, a multi-section incidence loss model is proposed. For the second limitation, more research work is suggested to investigate the effect of mixed-flow features at the MFT rotor inlet. As a contribution to investigate the mixed-flow feature at the MFT rotor inlet, different stator tilting endwall designs are numerically evaluated with computational fluid dynamics (CFD) tools. An MFT with well-documented experimental data is selected as the baseline and used to validate the CFD method. Performance improvement has been seen from those design, Under den pågående energiomställningen i samhället är turboladdning fortfarande en viktig teknik för fordonsindustrin för att minska bränsleförbrukningen och sänka utsläppen för sina fordon. Turboladdarens betydelsefullhet kan ses inom både konventionella drivsystem för fossila bränslen och framväxande applikationer, såsom ökat utnyttjande av biodrivmedel till-sammans med vätgasbränsleceller. För turboladdare till bilar har turbinen huvudsakligen två alternativa typer, dvs. mixade inflödesturbiner (MFT) och radiella inflödesturbiner (RFT). Dessa enheter är mogna och kommersiellt tillgängliga men ändå finns det en betydande förbättringspotential mot högre prestanda, mer robust drift och lägre kostnad. Med detta i åtanke är det övergripande syftet med denna studie att förbättra den aero-dynamiska designen och de aeromekaniska analysmetoderna för MFT och RFT. Specifika områden som behandlas är: aero-dynamisk mittsnittsanalys, vinklade statorändväggar och påt-vingad respons (forced respons). Ett verktyg för mittsnittsanalys har nyligen utvecklats för att förutsäga prestandakurvor. För RFT:er visar resultaten en generellt god överensstämmelse mellan den förutsagda prest-andan och presenterade experimentella data. För MFT:er har dock två begränsningar av förlustmodeller som används i mittsnittsanlys identifierats: radiell variation av inloppsvinkeln tas inte hänsyn till och prestationsvariationer vid olika hastigheter kan inte fångas av de undersökta rotorpassage-förlustmodellerna. För att övervinna den första begränsningen föreslås en flersektionsmodell för incidensförlust vid inloppet. För den andra begränsningen föreslås mer forskningsarbete för att undersöka effekten av mixat flöde vid MFT-rotorinloppet. Som ett bidrag för att utreda egenskaper för mixat flöde vid MFT-rotorinloppet utvärderas olika vinklade statorändväggs-designer numeriskt med CFD-verktyg (computational fluid dynamics). En MFT med väldokumenterade experimentella data väljs ut som basfall och används

This project aims to design a radial inflow microturbine that will be part of a system to generate both heat and electricity. Considering the specific power and the mass flow rates involved with the system, a radial inflow turbine was chosen. This type of turbine provides much larger power density in a single stage compared to the other types.

Psychoacoustic studies show that the level of perceived annoyance with respect to noise emitted by aircrafts engine positively depends on the sound pressure level of the tonal components in the frequency spectrum. Acoustic modes generated by the rotation of the rotor and the periodic interaction of the stationary and rotating blades in the turbomachinery parts of the aircraft engine are the main contributors to the emitted tonal noise. In order to develop mitigation measures for these modal sound fields, experimental investigations are carried out on turbomachinery test rigs. For high quality research data, similarity between measurements has to be accomplished, as even minor changes to reference conditions might impair the significance of measurements. For time-harmonic sound propagation in an inviscid and ideal flow, the Helmholtz number and the Mach number establish similarity conditions. This work addresses the establishment of similarity of modal sound propagation on test rigs where equality of the Mach number and / or the Helmholtz number cannot be met reliably between measurements. The investigation focuses on individual acoustic modes propagating in a circular duct carrying an axial uniform flow. Experimental investigations are carried out on a low-pressure air turbine test rig. The test rig is equipped with a so-called sound generator for the controlled excitation of acoustic modes of arbitrary order and at specific frequencies. Similarity of the propagation of excited modes is evaluated by analyzing the modal response function. Based on an analytical analysis of the collected measurement data and a post-hoc scaling approach, it is shown that the axial angle of the group velocity vector is a suitable parameter to establish partial similarity with respect to modal sound propagation in cases where similarity of the Helmholtz number and / or the Mach number cannot be achieved. A similarity relation between the three parameters is derived. A sensitivity analysi, Psychoakustische Studien zeigen, dass die empfundene Belästigung durch Fluglärm von dem Anteil der tonalen Komponenten im emittierten Frequenzspektrum des Triebwerks abhängig ist. Durch den Rotor und die Interaktion von rotierenden und stehenden Schaufeln im Triebwerk werden modale Schallfelder, so genannte akustisch Moden, generiert, welche als diskrete Frequenzen im abgestrahlten Spektrum auftreten. Experimentelle Versuche an Triebwerkskomponenten dienen der Entwicklung von Maßnahmen zur Reduzierung dieser modalen Anteile. Die Qualität der Messdaten ist dabei maßgeblich von der Einhaltung der Ähnlichkeit zwischen den einzelnen Messungen abhängig, da bereits minimale Änderungen in den Messbedingungen zu unterschiedlichen Ergebnissen führen können. Für die in dieser Arbeit betrachtete harmonische Schallausbreitung in einem angenommenen idealen nicht-viskosen Fluid, sind die Helmholtz-Zahl und die Mach-Zahl die bestimmenden Ähnlichkeitsparameter. In dieser Arbeit wird eine Methode zur Einhaltung von Ähnlichkeit in Bezug auf die modale Schallausbreitung vorgestellt. Die Methode konzentriert sich auf Prüfstande, bei denen bei veränderten Eintrittsbedingungen die Helmholtz-Zahl und die Mach-Zahl zwischen zwei Messungen nicht zuverlässig konstant gehalten werden können. Der Fokus liegt dabei auf der Ausbreitung einzelner Moden in einem axial durchströmten Rohr. Experimentelle Untersuchungen werden auf einem Niederdruck- Luftturbinenprüfstand durchgeführt. Im Eintritt ist ein Schallgenerator eingebaut, der die Anregung spezifischer akustischer Moden bei ausgewählten Frequenzen ermöglicht. Die Ähnlichkeit zwischen Messungen wird anhand der modalen Antwortfunktion bestimmt. Analytische Betrachtungen und eine nachträglich durchgeführte Skalierung der Messergebnisse zeigen, dass der Winkel zwischen dem modalen Gruppengeschwindigkeitsvektor und der Rohrachse geeignet ist, partielle Ähnlichkeit in Bezug auf die modale Schallausbreitung herzustellen. Eine Analyse der Ähnlichkeit

This paper presents a methodology to evaluate the technical state of a Francis turbine by shaft rotor dynamic simulation. There are several rotor dynamic criteria that define the technical state of a turbo-machine. To feed the shaft rotor dynamic model this delivers the required information to accomplish the technical assessment. The numerical rotor dynamic model uses as input, the field forces obtained by the fluid-solid interaction analysis undertaken over the blades of the runner. The rotor dynamic numerical simulations allow to determinate the record-in-time of the displacements of any point along the shaft. This information is relevant for diagnosis tasks, because it is possible to decompose it spectrally and to estimate the severity of the vibrations. Comparing the results of the numerical model against those obtained from machines that operates under normal conditions, it is possible to determinate the technical state of the turbo-machine. This allows studying the stability of the turbine working on several operation ranges. A Francis turbine is a very complex machine that involves many physical phenomena of different nature. In this way, the hydraulic input forces needed by the rotor dynamic model should not be assumed but calculated directly from the fluid interaction over the turbine structure.

Depuis quelque temps, un groupe de chercheurs du Groupe d'innovation Createk de l'Université de Sherbrooke travaille sur une nouvelle configuration de rotor de turbine qui utilise un carénage rotatif structurel pour tenir des pales en céramique sous compression, sous l’action du champ centrifuge. Cette configuration de rotor, baptisée Inside-Out Ceramic Turbine (ICT) vise à augmenter la température d'entrée de la turbine (TIT) pour les petites turbines, pour lesquelles le refroidissement et les techniques de fabrication complexes sont d'un coût prohibitif. Plusieurs prototypes et itérations du rotor ICT ont été testés au cours des dernières années, augmentant le temps de fonctionnement et la température d’opération atteignables. Au fur et à mesure que la confiance de l'équipe dans le rotor ICT s'améliore, les problèmes auxquels il est confronté deviennent importants à identifier et à résoudre. Cette thèse vise à étudier et à améliorer la fiabilité des pales en céramique dans des conditions normales de fonctionnement. Ceci est essentiel à l'adoption de la technologie ICT dans un grand nombre de moteurs. La thèse est découpée en trois parties : (1) isoler la cause la plus probable de défaillance des pales grâce à l'observation des résultats expérimentaux et numériques passés, (2) quantifier l'influence relative des principaux paramètres de conception sur la fiabilité des pales à l’aide d’un modèle numérique, et (3) tester des solutions potentielles qui ciblent les variables de conception les plus critiques, pour obtenir une meilleure fiabilité des pales ICT. Les pales étant en céramique technique monolithique, actuellement en nitrure de silicium, elles supportent mal les contraintes en tension. Le niveau de contrainte le plus élevé dans les pales s’avère être à l'interface avec les composants métalliques de support, car les pales sont maintenues en place par friction sous une force normale importante, et des contraintes élevées en tension se manifestent à l'interface., For some time now, a group of researchers in the Createk Innovation Group at Université de Sherbrooke have been working on a novel turbine rotor configuration which uses a structural, rotating shroud to compress ceramic blades under centrifugal load. This rotor configuration, dubbed Inside-Out Ceramic Turbine (ICT) aims at increasing turbine inlet temperature (TIT) for small turbines, for which intricate cooling and complex manufacturing techniques are prohibitively costly. Several prototypes and iterations of the ICT rotor have run over the last years, achieving consistently better run times and firing temperatures. As the team’s confidence in the ICT rotor improves, the issues facing it become important to identify and address. This thesis aims at investigating and improving reliability of the ceramic blades under normal operating conditions. This is central to the adoption of ICT technology in mainstream engines. The thesis is cut into three parts: (1) isolating the most probable cause of failure in the blades through observation of past experimental and numerical results, (2) quantifying the relative influence of the main design parameters on blade reliability through a numerical model, and (3) testing potential solutions which target the most critical design variables, to achieve a better reliability in the ICT blades. As the blades are made of monolithic technical ceramic, currently silicon nitride, they do not tolerate tensile stress fields well. The highest stress level in the blades was found to be at the interface with supporting metallic components, as the blades are maintained in place through friction under large normal force, and a strain mismatch is present at the interface. This leads to first reduce the number of interfaces to a minimum, i.e., only at the blade tip pressing up against the rotating structural shroud. Second, at this remaining interface, efforts to reduce coefficient of friction especially, as well as reduce thermal expansi

In the battle against climate change, humankind needs to develop alternative energy systems if it wants to survive on this planet. Fossil fuels, polluting the air with CO2, must make way for renewable sources so that climate change is put to a stop. Several new energy initiatives based on renewable sources are deployed worldwide, these however are mostly for electricity generation. There are elatively few zero emission alternatives developed for the energy demand from the transport sector, therefore, new small scale energy systems need to be developed in order to achieve the goals stated in the Paris agreement. The Hydrogen Roadmap” is a vital part of the European Union in achieving the Paris climate agreement, which uses hydrogen for future energy generation. Gas turbines, steam turbines and fuel cell applications are investigated thoroughly for small scale energy systems throughout the years. Fewer research is conducted about the integration of these three energy technologies and specially sparse research has been conducted in the area of pure hydrogen oxygen combustion for these energy systems, resulting in opportunities for development. This report introduces an alternative small scale power system suited for the newest inland shipping vessels. It proposes a basic design for a 3 MW SOFC integrated hydrogen oxygen fired combined power cycle, feasible within 10 to 20 years of research and development. First, the theoretical background for the research is elaborated covering the thermodynamics of traditional power cycles, exergy analysis theory and zero emission cycles such as hydrogen oxygen fuelled power cycles. The electrochemical research containing the fuel cell operating specifics and the advantages of integrating fuel cell stacks in power cycles is introduced next. The theoretical background ends with an elaboration on the preliminary design steps for power cycle components regarding turbomachinery and heat exchange equipment. After the relevant subjects reg, Mechanical Engineering | Energy and Process Technology

In this energy transition era, turbocharging is still an important technology for the automotive industry to reduce fuel consumption and lower emissions in its vehicles. This importance can be seen from both conventional fossil-fuel powertrains, and emerging applications, such as increased utilization of biofuels along with hydrogen fuel cells. For automotive turbochargers, the turbine has mainly two alternative types, i.e., mixed flow turbines (MFTs) and radial flow turbines (RFTs). These devices are mature and commercially available yet still have significant potential for improvement towards ensuring higher performance, more robust operation, and lower cost. With this in mind the overall aim of this study is to improve the aerodynamic design and the aeromechanical analysis methods for MFTs and RFTs. Specifically, the investigation covers three research topics: meanline method, stator tilting endwall design, and forced response analysis. A meanline method tool is newly developed to predict the performance curves. For RFTs, the results present a generally good agreement between the predicted performance and experimental data. However, for MFTs, two limitations of loss models used in the meanline method have been identified: spanwise variation of incidence at the rotor inlet is neglected; and performance variations at different speeds cannot be captured by the investigated passage loss models. To overcome the first limitation, a multi-section incidence loss model is proposed. For the second limitation, more research work is suggested to investigate the effect of mixed-flow features at the MFT rotor inlet. As a contribution to investigate the mixed-flow feature at the MFT rotor inlet, different stator tilting endwall designs are numerically evaluated with computational fluid dynamics (CFD) tools. An MFT with well-documented experimental data is selected as the baseline and used to validate the CFD method. Performance improvement has been seen from those design, Under den pågående energiomställningen i samhället är turboladdning fortfarande en viktig teknik för fordonsindustrin för att minska bränsleförbrukningen och sänka utsläppen för sina fordon. Turboladdarens betydelsefullhet kan ses inom både konventionella drivsystem för fossila bränslen och framväxande applikationer, såsom ökat utnyttjande av biodrivmedel till-sammans med vätgasbränsleceller. För turboladdare till bilar har turbinen huvudsakligen två alternativa typer, dvs. mixade inflödesturbiner (MFT) och radiella inflödesturbiner (RFT). Dessa enheter är mogna och kommersiellt tillgängliga men ändå finns det en betydande förbättringspotential mot högre prestanda, mer robust drift och lägre kostnad. Med detta i åtanke är det övergripande syftet med denna studie att förbättra den aero-dynamiska designen och de aeromekaniska analysmetoderna för MFT och RFT. Specifika områden som behandlas är: aero-dynamisk mittsnittsanalys, vinklade statorändväggar och påt-vingad respons (forced respons). Ett verktyg för mittsnittsanalys har nyligen utvecklats för att förutsäga prestandakurvor. För RFT:er visar resultaten en generellt god överensstämmelse mellan den förutsagda prest-andan och presenterade experimentella data. För MFT:er har dock två begränsningar av förlustmodeller som används i mittsnittsanlys identifierats: radiell variation av inloppsvinkeln tas inte hänsyn till och prestationsvariationer vid olika hastigheter kan inte fångas av de undersökta rotorpassage-förlustmodellerna. För att övervinna den första begränsningen föreslås en flersektionsmodell för incidensförlust vid inloppet. För den andra begränsningen föreslås mer forskningsarbete för att undersöka effekten av mixat flöde vid MFT-rotorinloppet. Som ett bidrag för att utreda egenskaper för mixat flöde vid MFT-rotorinloppet utvärderas olika vinklade statorändväggs-designer numeriskt med CFD-verktyg (computational fluid dynamics). En MFT med väldokumenterade experimentella data väljs ut som basfall och används

In this energy transition era, turbocharging is still an important technology for the automotive industry to reduce fuel consumption and lower emissions in its vehicles. This importance can be seen from both conventional fossil-fuel powertrains, and emerging applications, such as increased utilization of biofuels along with hydrogen fuel cells. For automotive turbochargers, the turbine has mainly two alternative types, i.e., mixed flow turbines (MFTs) and radial flow turbines (RFTs). These devices are mature and commercially available yet still have significant potential for improvement towards ensuring higher performance, more robust operation, and lower cost. With this in mind the overall aim of this study is to improve the aerodynamic design and the aeromechanical analysis methods for MFTs and RFTs. Specifically, the investigation covers three research topics: meanline method, stator tilting endwall design, and forced response analysis. A meanline method tool is newly developed to predict the performance curves. For RFTs, the results present a generally good agreement between the predicted performance and experimental data. However, for MFTs, two limitations of loss models used in the meanline method have been identified: spanwise variation of incidence at the rotor inlet is neglected; and performance variations at different speeds cannot be captured by the investigated passage loss models. To overcome the first limitation, a multi-section incidence loss model is proposed. For the second limitation, more research work is suggested to investigate the effect of mixed-flow features at the MFT rotor inlet. As a contribution to investigate the mixed-flow feature at the MFT rotor inlet, different stator tilting endwall designs are numerically evaluated with computational fluid dynamics (CFD) tools. An MFT with well-documented experimental data is selected as the baseline and used to validate the CFD method. Performance improvement has been seen from those design, Under den pågående energiomställningen i samhället är turboladdning fortfarande en viktig teknik för fordonsindustrin för att minska bränsleförbrukningen och sänka utsläppen för sina fordon. Turboladdarens betydelsefullhet kan ses inom både konventionella drivsystem för fossila bränslen och framväxande applikationer, såsom ökat utnyttjande av biodrivmedel till-sammans med vätgasbränsleceller. För turboladdare till bilar har turbinen huvudsakligen två alternativa typer, dvs. mixade inflödesturbiner (MFT) och radiella inflödesturbiner (RFT). Dessa enheter är mogna och kommersiellt tillgängliga men ändå finns det en betydande förbättringspotential mot högre prestanda, mer robust drift och lägre kostnad. Med detta i åtanke är det övergripande syftet med denna studie att förbättra den aero-dynamiska designen och de aeromekaniska analysmetoderna för MFT och RFT. Specifika områden som behandlas är: aero-dynamisk mittsnittsanalys, vinklade statorändväggar och påt-vingad respons (forced respons). Ett verktyg för mittsnittsanalys har nyligen utvecklats för att förutsäga prestandakurvor. För RFT:er visar resultaten en generellt god överensstämmelse mellan den förutsagda prest-andan och presenterade experimentella data. För MFT:er har dock två begränsningar av förlustmodeller som används i mittsnittsanlys identifierats: radiell variation av inloppsvinkeln tas inte hänsyn till och prestationsvariationer vid olika hastigheter kan inte fångas av de undersökta rotorpassage-förlustmodellerna. För att övervinna den första begränsningen föreslås en flersektionsmodell för incidensförlust vid inloppet. För den andra begränsningen föreslås mer forskningsarbete för att undersöka effekten av mixat flöde vid MFT-rotorinloppet. Som ett bidrag för att utreda egenskaper för mixat flöde vid MFT-rotorinloppet utvärderas olika vinklade statorändväggs-designer numeriskt med CFD-verktyg (computational fluid dynamics). En MFT med väldokumenterade experimentella data väljs ut som basfall och används

In this energy transition era, turbocharging is still an important technology for the automotive industry to reduce fuel consumption and lower emissions in its vehicles. This importance can be seen from both conventional fossil-fuel powertrains, and emerging applications, such as increased utilization of biofuels along with hydrogen fuel cells. For automotive turbochargers, the turbine has mainly two alternative types, i.e., mixed flow turbines (MFTs) and radial flow turbines (RFTs). These devices are mature and commercially available yet still have significant potential for improvement towards ensuring higher performance, more robust operation, and lower cost. With this in mind the overall aim of this study is to improve the aerodynamic design and the aeromechanical analysis methods for MFTs and RFTs. Specifically, the investigation covers three research topics: meanline method, stator tilting endwall design, and forced response analysis. A meanline method tool is newly developed to predict the performance curves. For RFTs, the results present a generally good agreement between the predicted performance and experimental data. However, for MFTs, two limitations of loss models used in the meanline method have been identified: spanwise variation of incidence at the rotor inlet is neglected; and performance variations at different speeds cannot be captured by the investigated passage loss models. To overcome the first limitation, a multi-section incidence loss model is proposed. For the second limitation, more research work is suggested to investigate the effect of mixed-flow features at the MFT rotor inlet. As a contribution to investigate the mixed-flow feature at the MFT rotor inlet, different stator tilting endwall designs are numerically evaluated with computational fluid dynamics (CFD) tools. An MFT with well-documented experimental data is selected as the baseline and used to validate the CFD method. Performance improvement has been seen from those design, Under den pågående energiomställningen i samhället är turboladdning fortfarande en viktig teknik för fordonsindustrin för att minska bränsleförbrukningen och sänka utsläppen för sina fordon. Turboladdarens betydelsefullhet kan ses inom både konventionella drivsystem för fossila bränslen och framväxande applikationer, såsom ökat utnyttjande av biodrivmedel till-sammans med vätgasbränsleceller. För turboladdare till bilar har turbinen huvudsakligen två alternativa typer, dvs. mixade inflödesturbiner (MFT) och radiella inflödesturbiner (RFT). Dessa enheter är mogna och kommersiellt tillgängliga men ändå finns det en betydande förbättringspotential mot högre prestanda, mer robust drift och lägre kostnad. Med detta i åtanke är det övergripande syftet med denna studie att förbättra den aero-dynamiska designen och de aeromekaniska analysmetoderna för MFT och RFT. Specifika områden som behandlas är: aero-dynamisk mittsnittsanalys, vinklade statorändväggar och påt-vingad respons (forced respons). Ett verktyg för mittsnittsanalys har nyligen utvecklats för att förutsäga prestandakurvor. För RFT:er visar resultaten en generellt god överensstämmelse mellan den förutsagda prest-andan och presenterade experimentella data. För MFT:er har dock två begränsningar av förlustmodeller som används i mittsnittsanlys identifierats: radiell variation av inloppsvinkeln tas inte hänsyn till och prestationsvariationer vid olika hastigheter kan inte fångas av de undersökta rotorpassage-förlustmodellerna. För att övervinna den första begränsningen föreslås en flersektionsmodell för incidensförlust vid inloppet. För den andra begränsningen föreslås mer forskningsarbete för att undersöka effekten av mixat flöde vid MFT-rotorinloppet. Som ett bidrag för att utreda egenskaper för mixat flöde vid MFT-rotorinloppet utvärderas olika vinklade statorändväggs-designer numeriskt med CFD-verktyg (computational fluid dynamics). En MFT med väldokumenterade experimentella data väljs ut som basfall och används

Les nouvelles réglementations en matière de contrôle des émissions sonores des futures générations d’aéronefs contraignent les motoristes à développer des systèmes de propulsion de moins en moins bruyants. L’étage de soufflante d’un turboréacteur étant la source de bruit la plus importante d’un avion en phases d’approche et de décollage, il convient alors de s’intéresser de près aux sources de bruit d’origine aérodynamique que l’on rencontre au sein de cet étage. En particulier, le manque de connaissances sur les phénomènes physiques à l’origine du bruit émis par l’écoulement de jeu en tête de pale de soufflante de turboréacteur a conduit à cette thèse. Cette dernière vise ainsi à reproduire de façon numérique, par l’utilisation de méthodes haute-résolution (LES pour Large-Eddy Simulation), l’écoulement de jeu autour de trois configurations particulières, puis à identifier les principales sources de bruit de jeu. La première configuration est composée d’un profil fixe placé entre deux plaques planes, avec la présence d’un jeu entre le profil et l’une des plaques. Cette configuration académique vise à mettre en avant les sources issues de l’écoulement de jeu sans prendre en compte l’ensemble des mécanismes que l’on rencontre au sein d’une turbomachine. Puis, une grille d’aubes de compresseur linéaire avec jeu constitue la seconde configuration à l’étude, afin de mettre en avant l’influence de l’effet de grille dans les mécanismes de production et de propagation d’ondes acoustiques issues de l’écoulement de jeu. Enfin, une pale de turboréacteur à double flux constitue l’application industrielle finale, afin de prendre en compte l’ensemble des mécanismes à l’origine du bruit de jeu, en particulier pour mettre en avant l’influence des effets de rotation. Les simulations numériques sont validées en comparant les résultats aérodynamiques et acoustiques aux résultats des études expérimentales effectuées sur les mêmes configurations. Puis, les sources de bruit sont analysée, Future aircraft propulsion systems have to face new regulations for noise emissions. De- creasing the noise emitted by a turbofan engine is now one of the main constraints for engine manufacturers. Fan noise is known as the major noise source at approach and take- off regimes for a modern turbofan engine, and in particular the tip noise source from the tip-leakage flow is lacking some physical understanding. Thus, the main purpose of this thesis is to needed to fully understand the main mechanisms that drive the formation and the propagation of the acoustic waves created by the interaction of the tip-leakage flow with the adjacent surfaces. The second goal of this thesis is to reproduce numerically the tip-leakage flow for three particular configurations using high-fidelity simulations (Large- Eddy Simulations), and then identify the main noise sources. The first configuration is composed of a fixed airfoil mounted between two flat plates, with a gap between the airfoil and one of the plates. This academic configuration aims at highlighting the tip-gap source only without taking into account other phenomena involved in the tip-leakage flow inside a turbofan engine. Then, a linear compressor cascade with tip gap constitutes the second configuration and allows identifying the influence of the cascade effects on the emission and propagation mechanisms related to the tip noise sources. Finally, a turbofan blade from a modern scaled turbofan engine represents the industrial test case in order to take into account all the mechanisms involved in the noise emission, especially to highlight the influence of the rotational effects. Numerical simulations are validated through compar- isons of the aerodynamic and acoustic fields with experimental results achieved on the same configurations. Then, the noise sources are analyzed thanks to the identification and the interaction of the main vortical structures from the tip-leakage flow. Finally, advanced post-processing t

In turbomachines, rotors and stators differ by the rotation of the former. Hence, half of each stage is directly influenced by rotation effects. The influence of rotation on the flow structure and its impact on the performance is studied through Wall-Resolving Large Eddy Simulations of a rotor with large relative tip gap size. The simulations are performed in a rotating frame with rotation accounted for through a Coriolis force term. In a first step experimental results are used to provide validation. The main part of the study is the comparison of the results from two simulations, one representing the rotating configuration, one with the Coriolis force removed, without any other change. This setup allows very clean assessment of the influence of rotation. The turbulenceresolving approach ensures that the turbulent flow features are well represented. The results show a significant impact of rotation on the secondary flow. In the tip region the Tip Leakage Vortex is enlarged and destabilised. Inside the tip gap the flow is altered as well, with uniformization in the rotating case. At the blade midspan, no significant effects are observed on the suction side, while an earlier transition to turbulence is found on the pressure side. Near the hub, rotation effects are shown to reduce the corner separation significantly., Funding was provided by the Deutsche Forschungsgemeinschaft (DFG), under FR1593/15-1 and MA4922/8-1 within PAK948. The authors would like to acknowledge stimulating discussions with the partners of this project. Computations were performed at the Centre for Information Services and High Performance Computing (ZIH) at TU Dresden., Postprint (published version)